The invention relates to a delivery table for flat material, in particular sheet paper, with a safeguard so that the material does not slide on the delivery table.
A delivery table of this kind is disclosed in DD-247 433 A1 in which the latter is constructed as a sheet deliverer for a printing press and a stop serves as a safeguard, against which stop the sheets being conveyed strike and deliver themselves. Material to be delivered bounces back against such stops and the danger exist that during delivery it will not sit exactly at the stop. Moreover, the danger exists that, as result of vibrations, the material delivered, possibly even an entire stack of material, will move away from the stop because the material or stack exhibits too little friction vis-à-vis the delivery table.
The object of the invention is therefore to construct a delivery table of the kind stated at the outset such that exact and stable positioning of the flat material can be achieved.
The object is solved in accordance with the invention in that the safeguard to prevent sliding of the flat material is constructed as a surface disposed in the back area of the delivery table, viewed from the direction of conveyance, exhibiting high friction vis-à-vis the flat material.
The advantage of the invention consists in the exact positioning of the first sheet which is securely positioned by means of the high friction, whereby the position of additionally stacked sheets and, accordingly, the entire stack, is assured. The high friction surface additionally absorbs the movement of the first sheet and consequently prevents a slanting position from arising. Because the high friction surface is provided only at the end of the delivery table, the sheets of material to be delivered are otherwise able to freely slide and, therefore, surely reach their delivery position. By virtue of the construction in accordance with the invention, the provision of a stop can be dispensed with, which has the added advantage that the material to be delivered can no longer be damaged by striking against a stop.
One refinement of the invention provides that the delivery table is equipped with a conveyance and positioning device. The latter preferably acts together with the high friction surface in such a way that positioning takes place in a defined delivery position with the aid of the surface. This can be effected for example, in that, after reaching the delivery position, a flat material is pressed against the surface by means of at least one holding-down clamp.
The aforementioned delivery and positioning device can be refined in the most varying manner. One proposal provides that, disposed at the back area, the conveyance and positioning device exhibit horizontally and vertically movable tongues, actuatable and horizontally movable rollers and at least one horizontally and vertically movable holding-down clamp, with driving gears and control mechanism provided in such a way that a flat material lying between the rollers and tongues is conveyed by the rollers over the high friction surface into its defined delivery position, that the holding-down clamp then presses the flat material against the high friction surface, the rollers are lifted, the tongues withdrawn from the delivery table counter to the direction of conveyance and that to convey additional material, the holding-down clamp is lifted and withdrawn from the delivery area and that the tongues and rollers are again positioned over the back area. This or similar conveying and positioning units have the advantage that they convey the material to be delivered over the surface with high coefficient of friction, thereafter effecting immovable securing of the flat material by at least one holding-down clamp pressing the material against the surface with high coefficient of friction.
The high friction surface can extend over the entire width of the back area of the delivery table. It is expediently formed by a strip, which can be glued to the delivery table, in which case it has been shown to be advantageous if the strip exhibits a surface made of rubber.
In addition, guide strips connecting to the surface with increased friction and extending in the direction of conveyance can be disposed which exhibit lower friction vis-à-vis the flat material. This ensures that the flat material slides surely and without alignment error into the delivery position and can be positioned there in the above-described manner.